高强超微外加剂对喷射混凝土力学性能及回弹率的影响研究

Study on the Influence of High Strength Ultramicro Admixture on Mechanical Properties and Rebound Rate of Shotcrete

普通喷射混凝土在喷射过程中回弹率高,粉尘量大,强度不容易达标,特别是在富水区,这些情况更为严重,在喷射混凝土中掺入一种高强超微外加剂,用来改善喷射混凝土的力学性能,降低喷射混凝土的回弹率及粉尘量。本文将高强超微外加剂应用于喷射混凝土中,研究了其对喷射混凝土力学性能及回弹率和粘结强度的影响。试验结果表明:高强超微外加剂能够显著提高喷射混凝土的抗压强度和抗折强度,在C25喷射混凝土中,高强超微外加剂掺量为6%时,喷射混凝土28 d抗压强度与抗折强度与不掺高强超微外加剂组分别提高6.4%与32%;添加高强超微外加剂的喷射混凝土在工程应用中回弹量平均只有7.3%,比普通喷射混凝土降低28%,粘结强度最高为2.29 MPa,是普通喷射混凝土的3~4倍。

Ordinary shotcrete in the process of spraying rebound rate is high,large amount of dust,strength is not easy to reach the standard,especially in the water-rich area,these conditions are more serious,in shotcrete mixed with a high strength ultramicro admixture,used to improve the mechanical properties of shotcrete,reduce the rebound rate of shotcrete and dust.In this paper,high strength ultramicro admixture is applied to shotcrete and its effect on mechanical properties and rebound rate of shotcrete is studied.The experimental results showed that the high-strength ultramicro admixture could significantly improve the compressive strength and flexural strength of shotcrete.In C25 shotcrete,when the dosage of high-strength ultramicro admixture was 6%,the 28d compressive strength and flexural strength of shotcrete increased by 6.4%and 32%,respectively,compared with the group without high-strength ultramicro admixture.The average rebound of shotcrete with high strength and ultra-fine admixture in engineering application is only 7.3%,28%lower than that of ordinary shotcrete,and the highest bond strength is 2.29mpa,which is 3~4 times of that of ordinary shotcrete.